Photographic processing



Sept. 30, 1952 P. RAIBOURN PHOTOGRAPHIC PROCESSING Filed Jan. 15, 1947 fwn?. Ecm

Patentecl Sept. 30, 1952 UNITED STATES PATENT oFFIcE rnorocnnrrno PROCESSING Paul Raibourn, Southport, Conn. Application January 13, 1947, serial No. 721,780

3 Claims.`

This invention comprises a method of accurately controlling penetration of a photographic lm processing Solution into a photographic emulsion.

The broad object of this invention is to provide a substantially automatic method whereby the penetration or diffusion of a processing solution into a photographic film emulsion can be accurately determined and controlled.

A more specific object of the invention is to providea method of this .type for determining` and controlling the penetration of processing solutions into a particular emulsion layer of a multiple emulsion lm such as a monopack lm.

A more detailed object of this invention is to provide such a method for use with the method disclosed in my copending application Serial No. 720,931, led vJanuary .8, 1947, now abandoned, for Method of Producing Color Separation Negatives.

Othei` and'more detailed objects of the invention will beapparent from the following description of one mode of practising it, as well as practising it with the variations suggested.

This invention resides substantially in the steps and series of steps all as hereinafter set forth in detail in connection with the attached drawings illustrating one embodiment of the apparatus used with the'method of this invention.

In the accompanying drawings,

Figure 1 is a diagrammatic and schematic view i of apparatus with which the `method may` be provides a means for practising the method herein disclosed; and

Figure 5 is a chart illustrating certain principles involved in this method.

As disclosed in greater detail in my above mentioned application, but sufciently disclosed herein to understand how this invention is utilized, in the processing of multiple emulsion lms such as monopack film for ythe preparation of colorseparation negatives therefrom, the processing solutions after exposure of the kiilm are selectively diiused into the emulsion layers. Such treatment of a monopack lm will be assumed` as an aid to disclosing this method;

v A monopack film will be considered having a transparent plastic base on which are superposed three emulsion layers separated by two gelatin layers. The bottom layer directly superposed on the plastic base comprises a red sensitive emulsion upon which in turn is coated a layer of clear gelatin and upon that a layer of green sensitive emulsion. Coated on the green sensitive emulsion isa yellow dyed gelatin layer, and onthat layer is coated a blue sensitive or so-called "color blind emulsion. Initially a motion picture monopack lm will be considered such as that illustrated in Figures 2 and 3. It will comprise a physical structure II] having one, or as more common, two sets of sprocket perforations I I extending along the side edges thereof between which lies the picture area I2. This nlm, as pictorially illustrated in Figure 3, comprises the clear plasticv base I4, the red sensitive emulsion I5, the clear gelatin layer I5, the green sensitive emulsion layer I1, the yellow dyed layer I8, and the blue sensitive layer I9. The relative arrangement'of the layers is, of course, subject to variation by appropriate change, as is well understoodin the art. It is equally well understood that the iilm of Figures 2 and 3 is a well known article of commerce. f

Assume that a monopack nlm of this type has been correctly exposed, developed and xed to form black and White silver images in each emulsion layer. Assume further that itis desired to produce color separation negatives from these three silver images. As set forth in the above mentioned application, it is possible toproduce separation negatives from the layers I9 andr I'I above and below the yellow dyed gelatin layer I8 by bleaching of all the images in the monopack to silver halide and exposing it to a blue light from below the layer I8 and redeveloping the images contained in the exposed layers. The silver halide image in the unexposed layer can now be removed by suitable and well known silver halide solvents.

However, the above optical method cannot serve to differentiate as between the layers I1 and I5 which are separated by the clear gelatin layer I 6, or in a, modication where a clear separating -layer is not employed. Thus, later in the process when preparing color separation negatives from the green layer I1 and the red layer I5, it is necessary to selectively process these layers. For example, during the process as disclosed in the above entitled application, it becomes ultimately necessary to convert the image in the green layer II to a silver halide image and bleach or remove it without affecting the red layer I5. This involves the selective diffusion or penetration of the solvent into the red layer, in which operation it is desirable to stop the penetration of the solvent as soon as the image is cleared from the layer.

The method of this invention provides avery simple and eifective procedure for determining when the image in the green layer is clear so that the penetration of the solvent can be stopped. In accordance with this invention thereris applied either during the original exposure or during later processing, a xed frequency sine wave image on the nlm which can be likened to a.

. length.

sound track such as is commonly used in talking pictures. For example, a 1000 cycle xed frequency sine wave sound track can be applied to the lm by means of apparatus which is well understood by and available to the art for this` purpose.

In accordance with this invention it is preferable to apply this sine wave record at any part of the space beyond the inner edges of the perforations II. For example, the image can be impressed between the broken parallel lines, .as indicated at I3 in Figure 2, where, as shown',.it overlaps in part at least, the sprocket perforations at that side of the nlm. According to the assumed example, the Ygreen layer I is under consideration, the 1000 cycle sound track is printed in the green emulsion layer` with green 'light through a sharp cutting green filter to form an image which has been diagrammatically illustrated at in Figure 3; This connes the sound track to the middle emulsion layer I1,`and1'of course, it is clear that `this sound track should be printed in prior'to any processing of the monopack, that is while it is still normally'light sensitive. Exposureby green light insures that the record 20 will be conned to the green sensitive layer. This soundtrack 20 may bel printed in by means of the variable density type ofrecording equipment so as toy form a soundtrack which when developed would appear as indicated at 20 in Figure 5. The density 'of thissou'nd track is preferably controlled so' as to bearrthe proper relation to the density of` the picture image in the green layer. The proper density can easily be determined by experience, it being recalled that the monopack has been assumed to be properly exposed. Skilled photographers will, thereforaby experience, very quickly know the required density for the sound track. 1 As will appear later, the density of the sound track should be sunicient sol that when all the silver therein has been reduced or dissolved out all the .silver in the green emulsion layer will have been re duced or dissolved out. The 'densest portion of the sound track will, of course, depend upon the amplitude of the xed frequency signal 'recorded in the sound track, and this amplitude will be selected to attain the above result.

The 'exposed monopack with its gelatin images of the scene photographed and of the sound track is then fed from a supply reel 2I into a de veloping tank 22 which has been divided into a series of imaginary zones A, B, C and D, as diagrammatically illustrated in Figure 1, through which the iilm I0 progresses successively over a series of guide rollers 23 and 2li. At points intermediate the imaginary sections are provided iilm absorbing and supply devices, `diagrammatically illustrated as frameworks 25, 3U and 3I,'suspended by means of a cable and weights 29 on overhead pulleys 28. Suspended from lthe framework are the upper guide rolls and thek lower guide rolls 21. The lower guide rolls 24 and 2l For description, assuming that the lm in the section B is moving more slowly than the lm in thesection C, then the nlm stored on the second framework will be absorbed therefrom by reduction in length of the bight for the frame 30. Assuming that the number of upper and lower sets of rollers on the frames 25, 30 and 3I can be increased as desired, a considerable capacity for-storage and supply of film to make up the difference in speed between anyl two sections will be available, all as is well understood in the art.

As is clear from Figure 1, the lm issues from each imaginary section and passes through the points PI, P2 and P3. At these points the pick-up mechanism'of the left-hand portion of Figure 4 can be placed.' Thus at the `point PI there is provided a light source I3 with a suitable lens system and slit, as is Well known in the sound picture art, to focus the light on the sound track 20. Opposite .this slit is placed a photo-electric cell I3 which is connected lby the wires '3 4 to the input of a suitable vacuum tube amplifier 35. There is similarly disposed at the point P2 another light source lens system and slit 3G with cooperating photo-electric cell 31 feeding the inputof the amplifier 35. Finally, at the point P3 is another light source lens system and slit 38 cooperating with the photo-electric cell 39 which feeds the amplier 35. The output ofthe vampliiier is connected by theleads 40 to suitably designed iilters 4I, 42 and l43, respectively feeding the loud speakers 4Q, 45 .and-46, or other suitable forms of indicating Ydevices such as meters for visual as vdistinguished from audible reading.

In processing the iilm in the tank 22, it is preferable to use a sub-proportional reducer or solvent so loaded as to -be of slow diffusion rate, so that it will destroy the low densities faster than the high densities in the emulsion layerf being treated, that is, in theassumed example, the greenemulsion layer I1. As the nlm I0 progressesthrough the rst imaginary section A, thevsub-proportional reducer with whichv the tank 22 isycharged will begin to penetrate the layer II (the blue record image in the top layer having previously been removed as explained above). As this reducer penetrates this layer it will begin to reduce the silver halide image, and being'a sub-proportional reducer will clear out the image in the less denser areas more quickly than in the high density areas. Of course, this action will occur not only in the picture areas I 2 of the lm, but also in the sound track area. When the `film reaches the pick-up point PI, the image in the sound track 20 will have been reduced and of course more rapidly in the lighter areas than in the denser or signal peak areas. The movement'of the sound track past the pick-up point PI will result in the generation of a pulsatingy current of a certain magnitude such as that represented by the curve PIR (see Fig.- 5). This curve has been plotted with intensity or amplitude versus film length. As the same point onthe lm progresses through the imaginary section B it will be further reduced so that by the time it reaches the point P2 the currents generated will be of lower magnitude as repf resented by the curve PZR, and nally at the point P3 the magnitude of the current will have been further reduced, asl represented by the curve PSR. Of course, ultimately when the image in the sound track has completely disappeared, the current in the output of the photocell 39 will not be pulsating but will be a direct current.

The different currents of all the photocells will be mixed and fed to the amplier where theyare amplified to the desired degree and then fed selectively through the filters 4l, 42 and 43, so as to operate the indicating devices 44, 45 and 46.

rIt will'be assumed that the lter 4l is designed so that the device 44 reads the signal of the photoelectric cell 33 and the device 45 will read the signal of photocell 3l, and the device 46 will read the signal of the photocell 39. Thus the operator by reading the signals of the devices 44, 45 and 46 can control the speed of operation of the nlm in the various sections so that when the lm l0 emerges at the exit end of the tank 2'2 the image in the green emulsion layer will have completely disappeared while insuring that the film has not remained in Athe solution any longer than is necessary to attain this result. Those skilled in the art will understand that the use of a sub-proportional reducer has the eiect of rst reducing the low densities very rapidly, and then at the end clearing up the high density areas very rapidly, since in the meantime they have become low density areas.

As a further explanation, it will be noted that if by experience the signal of the device 44 indicates that at this point the image is disappearing too slowly, the film speed in the section A can be slowed down and vice versa, if the image is disappearing too rapidly the lm speed can be increased. As the speed of the film in each of the imaginary sections can be independently controlled, it is clear that an experienced operator reading the signals of the devices 44, 45 and 46 canso control the overall speed of the film I0 through the tank 22 that it can be caused to issue from the tank at just the right time, that is just after complete reduction of the image in the green layer. This provides insurance against diffusion or penetration of the reducer into any of the other layers beyond the very minimum penetration which necessarily is inherent in processing of this type.

It should be noted in passing that the selection of three points Pl, P2 and P3 was made for descriptive purposes, since in some cases only two conversion points may be necessary, and in others more conversion points may be necessary.

Itis obvious that if the sound track 2D overlaps the perforations Il of the film the movement of these perforations through the conversion point will generate a pulsating current to a frequency characteristic determined by the speed of the lm. Thus there will be generated in each photo-electric cell a current corresponding to those periorations, and in designing the amplifier and the filters 4|, 42 and 43 provision can be made to completely suppress this component of the signal so that it will not appear at the indicating devices 44, and 46,.

It is, of course, recognized that changing the speed of movement of the lm through the solution will cause some change in pitch of all the signal components generated at the pick-up point, but this Will not disturb the usefulness of the process since the operator'is particularly interested in the magnitude of'the components as indicated by the devices 44, 45 and 46 rather than thefrequency thereof. f l

It is also apparent to those skilled in the art that the process herein disclosed is not limited to determining and controlling the reduction of the image in only one emulsion layer as by simple duplication of this mechanism it can be made to indicate the penetration of the solvent and the reduction of the 'image' in different layers, -in which event the frequency of the sound track signal would preferably be different for each layer, in which event frequency as well as amplitude of the indicated current would be read in order to understand the yprogress of reduction in each'layer.- f

Those skilled' in the art' will also appreciate that this process is not limited to use in a system where the film moves. For example, thesame principles can be applied in the processing of still pictures ias distinguished from motion pictures, in which case the monopack lm would as before be provided with a sound track. However, as the film would be stationary during processing, a spot of light can be made to move with respect to the sound track rapidly over the length thereof by suitable mechanical or optical means, so as to produce the same relative movement of nlm and light spot, with the result that the rate of reduc'- tion of the silver image could be read and processing stopped when the signal disappears.

It is apparent, therefore, that the subject matter of this invention is capable of application with various forms of equipment, all of which are well known to those versed in this art. I do not, therefore, desire to be limited to the details of the process herein disclosed, or by reason of a particular apparatus by means of which the process is practiced, but preferably-the scope of my invention is to be determined by the appended claims.

What is claimed is:

1. A method of indicating the penetration of a processing solution into an emulsion layer of a multiple emulsion film, comprising the steps of exposing said film to form a latent scene image in each layer and to form a variable density signal image in at least one layer, the density of said signal image being substantially equal to the maximum density of said scene image, processing said lm to form silver images of all of said exposures, bleaching said film, processing said lm to reduce the density of all of the images in the layer containing said signal image, continuously moving said lm during said last processing step, converting said signal image at successive time intervals of the reducing process to sensible signals indicative of the extent of reduction of the scene image at said intervals, and Varying the relative rate of movement of said film in zones between successive points represented by said successive time intervals whereby complete reduction is attained at the time the lm reaches the last conversion point.

2. A method of processing an exposed undeveloped multiple emulsion film, comprising the steps of printing a signal track in the form of a variable density record of a fixed frequency signal of predetermined magnitude in one of the layers of said lm, the density of said signal track being substantially equal to the maximum density of exposure in that layer, developing and fixing said nlm, bleaching said film, processing said film to reduce the density of all the images in the L7 layer .containing said 'signal track, and converting fthe signal track image at successive stages .0f :development `into .sensible signals to indicate when the images in that layer havejbeen reduced ltoa:desiredextentl 3.,A method of processing fan exposed undeveloped :multiple ,emulsion nlm, comprising the steps of ,printing a signal .trackin the form :of a variable density record o'f fa'xed frequency signal of .a :magnitude to produce :a yciensity'inthe soundtrack :substantially -equal to the maximum density in .the scene image -in one of the layers of zsaidlm, the density .of -saidsign'al track- :being :Substantially equal to the maximum density of exposure in that layer, developing and .xing saidv lm, ybleaching said lm, `processing said lm to reduce the density of all the images .in'the layer containing said signal track, and converting thefsigngal track image .at successive stages .of .development vinto sensible :signals to indicate .REFERENCES CITED The following references are 'of record `inthe 'file of this patent:

UNITED STATES PATENTS 10 Number vName Date 1,956,122 l Gaspar Apr. f24, 1934 2,059,884 Mannes et a1. .Nov..3, 1936 2,059,887 Manneset al. Nov. 3, 1936 2,166,617 Weber et al. --.July 18,'1939 2,224,163 Sease et al Dec. 10., 19.40 2,269,161 Morse Jan. v.6, .1942

FOREIGN PATENTS ,-Num'ber Country Date '726,513 France Mar. y'7,1932 

1. A METHOD OF INDICATING THE PENETRATION OF A PROCESSING SOLUTION INTO AN EMULSION LAYER OF A MULTIPLE EMULSION FILM, COMPRISING THE STEPS OF EXPOSING SAID FILM TO FORM A LATENT SCENT IMAGE IN EACH LAYER AND TO FORM A VARIABLE DENSITY SIGNAL IMAGE IN AT LEAST ONE LAYER, THE DENSITY OF SAID SIGNAL IMAGE BEING SUBSTANTIALLY EQUAL TO THE MAXIMUM DENSITY OF SAID SCENE IMAGE, PROCESSING SAID FILM TO FORM SILVER IMAGES OF ALL OF SAID EXPOSURES, BLEACHING SAID FILM, PROCESSING SAID FILM TO REDUCE THE DENSITY OF ALL OF THE IMAGES IN THE LAYER CONTAINING SAID SIGNAL IMAGE, CONTINUOUSLY MOVING SAID FILM DURING SAID LAST PROCESSING STEP, CONVERGING SAID SIGNAL IMAGE AT SUCCESSIVE TIME INTERVALS OF THE REDUCING PROCESS TO SENSIBLE SIGNALS INDICATIVE OF THE EXTENT OF REDUCTION OF THE SCENE IMAGE AT SAID INTERVALS, AND VARYING THE RELATIVE RATE OF MOVEMENT OF SAID FILM IN ZONES BETWEEN SUCCESSIVE POINTS REPRESENTED BY SAID SUCCESSIVE TIME INTERVALS WHEREBY COMPLETE REDUCTION IS ATTAINED AT THE TIME THE FILM REACHES THE LAST CONVERSION POINT. 